Recently, a rotary drum collator has been invented that provides a much higher speed of collation. The present invention is an improvement on the collator disclosed in patent application Ser. No. 410,900 filed Oct. 29, 1973; now U.S. Pat. No. 3,970,297.
It naturally occurs that timing, phase and angle relationships between interdigitating parts of the collator are very critical. The inventive collator as described in the above application, features a rotary drum having a series of pockets for storing sheet material. The sheets are removed from the pockets to provide collations. The removal of the sheets is accomplished by rotating withdrawing arms that sweep into the rotating pockets of the drum, and frictionally remove the sheets therein disposed.
As the sheet material becomes depleted, the phase or timing angle of the rotating arms must adjust to the changing contact point for the sheets. Heretofore, a timing chain drive has provided the proper advancement of the phasing of the rotative withdrawing arms with respect to the remaining material in the drum. It has been discovered, however, that this timing chain drive only operates in the intended manner, when a standard sheet material thickness is employed. Material of a different sheet thickness is depleted from the pockets of the drum at a different rate. That is to say, that the depth or level to which the remaining material will fall within each pocket will depend upon the thickness of the sheet, i.e. the removal of a quantity of thicker material will provide a lower level of remaining material within each drum pocket, than the removal of an equal number of thinner sheets. The depth of the remaining sheet material is important to the operability of the device, because the contact point of the remaining material with the rotative arms will change as the material is depleted. Therefore, if the sheet level falls faster or slower than those standard sheet thickness for which it is designed, the collating device will eventually fail to properly operate. In other words, the rotative withdrawing arms will quickly go out of contact synchronization with the drum material.
The invention therefore, contemplates providing a sheet thickness control. This control adjusts the advancing of the phase of the withdrawing arms to allow for a greater or lesser depletion level of the remaining sheets throughout the drum.